How can I stop my iPhone camera roll pictures from converting to .heic format when sent using iMessages?

I’m using iPhone 13 pro max on iOS 15.4.1. I have camera formats setting on “most compatible”. When I take a picture with iPhone, the picture is in .jpeg format. However when I share the same pictures via iMessage, they are being converted to .heic format. How do I stop this conversion and keep the photos in .jpeg format while continuing to use iMessages to share photos ? Here is screenshot of photo taken with phone, copied from camera roll to "Files" on iPhone, shows as .jpeg. Here is the same picture after I iMessage it to myself and drag and drop on desktop and File info. Sorry I had screenshot it as I cant upload .heic.